Often when inflating tires, means are not readily available for indicating or limiting tire pressure. Some tires, such as those used on bicycles, have relatively small internal volume and extreme caution must be accordingly exercised because maximum pressure can be quickly reached and exceeded.
Inflation of small capacity tires is frequently performed at a service station pump or, alternatively, by means of a hand pump or foot pump. Service station pumps are not particularly suitable for such tires. First, the bellows of such pumps have a relatively large capacity, since they are primarly adapted to fill high capacity tires such as those used on automobiles. Accordingly, a relatively large volume of air is pumped for each "pound" of pressure signified by the bell on most such pumps. The large pump capacity can easily overpower the back pressure inside a small capacity tube and overinflate the tire, sometimes with serious consequence.
Secondly, there is a certain degree of inaccuracy in meters associated with service station pumps. Owing to the large volume of air associated with each "pound" of pressure produced by such pumps, the slight inaccuracies which are tolerable for high capacity tires, are undesirable for low capacity tires.
Accordingly, it is common for users of low capacity tires to inflate the tires with smaller capacity hand pumps and foot pumps. Since a small volume of air is introduced into the tire with each successive pumping motion, the danger of overinflation is decreased. This requires the user to own such a hand or foot pump, is slow, and requires phsyical effort on the part of the user.
In my U.S. Pat. No. 3,994,312 issued Nov. 30, 1976, the contents of which are hereby incorporated by reference, an inflation pressure regulator is disclosed which comprises a tube extending into the hollow interior of a housing. A collar is slidably mounted on the tube and opposingly acted upon by a coiled spring on one side and tire pressure on the other side. The spring biases the collar into a sealing position whereby the pressure source and tire are coupled for inflation of the tire. When the tire pressure exceeds the pressure exerted by the spring, the collar slides against the spring and couples the pressure source to an exhaust aperture in the side of the regulator housing, bypassing the tire.
While the aforementioned regulator provides significant advantages over those which were known in the art, it is an object of the present invention to provide an improved regulator which is suitable for small capacity, high pressure tires such as those used on bicycles, and still suitable for large capacity, low pressure tires. (Although the terms "low pressure" and "high pressure" are relative, those skilled in the art will recognize that "low pressure" typically denotes the 20-40 psi, while "high pressure" denotes 60-150 psi.)
Because only small incremental volumes of air are pumped into tires by hand pumps and foot pumps, it is desirable that an inflation pressure regulator used wth such a pump minimize leakages of the type which occur as seals become worn, thereby maximizing the quantity of air flowing into the tire.
Additionally, the seal of a regulator particularly adapted for small capacity, high pressure tires is subjected to high differential pressure. Accordingly, the seal for such a regulator is vulnerable to leakages which can develop when sliding seals are subject to friction wear over a period of time. It is accordingly desirable to provide a seal arrangement in which wear is minimized, thereby minimizing leakage and increasing the life of the regulator.